THIS invention relates to wire saws, and particularly to diamond wire saws.
It has been proposed to use diamond wire saws in the mining industry to cut slots in the rock mass in a mine. The diamond wire saw itself will usually comprise a length of steel wire carrying spaced apart, diamond-impregnated beads. Researchers in this field have identified jamming of the wire saw in the slot as a major problem in the implementation of diamond wire sawing proposals. In addition to jamming, problems can also be encountered, after temporary cessation of a sawing operation, in re-threading the wire saw through the slot when sawing is to start again.
It is believed that jamming of the wire saw in the slot is attributable to three main phenomena:
1. Rock movements which give rise to slot closure. These movements may be due to the elastic behaviour of the rock or discontinuities such as faults, joins and stress fractures in the rock mass. PA1 2. Entrainment by the wire saw of rock fragments which can cause jamming because of the close tolerance between the beads and the slot. PA1 3.Failures in the jointing of the wire saw itself. With the saw being under substantial tension during sawing, any failure of this type can cause the wire to spring back into a previously cut part of the slot where some closure has already taken place and where jamming is possible.
Whatever the cause of a jam, the only technique presently available to free the wire for resumption of sawing is conventional mining of the rock mass in which the saw is jammed. This is however time consuming and not always successful. In addition, conventional mining may damage the jammed wire saw.
An object of the present invention is to reduce the risk of the wire saw jamming in the slot.